The use of a sweeping jet fluidic oscillator for issuing a sweeping jet of air to, for example, clear the windshield of an automobile, is known in the art. In the above-identified related application Ser. No. 522,884 of Stouffer, one embodiment uses a continuous inertance loop fluidic oscillator in which a cross-over type fluidic oscillator has a pair of converging sidewalls leading to a common outlet with the air jet issuing from the power nozzle being caused to shift from one side of the chamber to the other and issue in a sweeping fashion through the common outlet by virtue of the action of a continuous inertance loop connecting control ports at each side of the air jet as it issues from the power nozzle. In the above-identified related application of Boone et al., the oscillator portion is made relatively short and instead of a diverging-converging cross-over type chamber fluidic oscillator element, the sidewalls of the interaction region diverge from each other to form an elongated slot to accomodate the sweeping angle of the oscillator. The pair of control ports immediately adjacent and downstream of the power nozzle are connected to a continuous inertance loop with several different techniques being utilized for accomodating the inertance loop, which is of a length and cross-sectional area so as to assure that the frequency of oscillation is below about 12 Hz for proper defrosting of the windshield. In the above-identified related application of Stouffer Ser. No. 748,065, the inertance loop has a pair or matching sections for coupling to the control ports of the oscillator, a pair of loop sections connected to the respective ends of the matching sections, a pair of transition sections coupling the ends of the loop sections to a cross-over or common section which is substantially flat and parallel to the plane of the fluidic element.
The present invention is an improvement on the fluidic oscillator disclosed in the above-identified related applicatains, and especially the fluidic oscillator disclosed in the above related application of Boone et al.
It is an object of the invention to provide an improved fluidic oscillator; more particularly, a further object of the invention is to provide an improved fluidic oscillator element which alternately issues slugs of concentrated air and is relatively short, easier and less expensive to fabricate, and has particularly unique applicability to defrost/defog function of vehicle windows.
According to this invention, the fluidic oscillator has a relatively short length so that it can be incorporated under the dash/instrument panel of an automotive vehicle for distributing defrost/defog air on both the driver and passenger sides of the vehicle to thereby rapidly and efficiently clear the windshield of frost and/or fog. The oscillator includes a power nozzle having a predetermined cross-sectional area, an interaction region defined by ceiling and floor walls and a pair of diverging sidewalls flaring to an outlet. A pair of control ports on the opposite sides of the interaction region and in advance of the diverging sidewalls, are interconnected by a continuous inertance loop or member. According to this invention a leaky splitter is located proximate the center of the outlet and modifies the distribution pattern of the air so that for the defrost/defog operation of a vehicle windshield, for example, essentially two alternating jets or slugs of defrost/defog air are alternately directed at predetermined positions and angular orientations on the windshield, each of the two jets being of full energy content and not difused. The leaky splitter is comprised of a necking or pinching end of the floor and ceiling walls proximate the center of the outlet and includes a pair of sweep angle enhancing vanes spacedly located to each side of the neck end or pinched end ceiling and/or floor walls.
Since it is desirable that the driver side be first cleared of frost or fog, the sweep angle enhancing vanes are biased or offset toward the passenger side so that the largest opening is oriented and aimed towards the driver's side of the windshield and the smallest opening is oriented or aimed toward the passenger side of the windshield. In a preferred embodiment, the floor and ceiling walls have angles of about six degrees to ten degrees to the axial center line of the interaction region to provide an expanding outlet which is needed for interaction regions which are under about 2.5 W in length where W is the width of the power nozzle. This space is needed to allow the jet to expand in the interaction region so as to not create a back pressure at the control ports which would interfere with the oscillation. In a preferred embodiment, the power nozzle has an aspect ratio of about 1:1 which means that it is about as wide as it is high, and that each of the two jets issuing through the sidewalls is approximately of the same cross-sectional shape and slightly larger in cross-sectional area. Thus, the invention in effect is switching the jet issuing through the power nozzle first through one side of the outlet and then the other due to the action of the leaky splitter. That is, as the jet is switching from one of the diverging sidewalls towards the other of the diverging sidewalls, it impinges on the leaky splitter for a very short period of time. The splitter is relatively a large element but due to the leakiness of it, its impedance is significantly lower than a non-leaky splitter and hence does not adversely effect oscillation.
In addition, the distribution can be tailored by the addition of various thickness to the pinching end of a floor and ceiling to achieve better tailoring or distribution of the jets impinging upon the windshield and thereby effect cleaning of other areas of glass (such as side windows) after clearing of the main or viewing areas or see areas.
It will be appreciated that while the invention finds particular applicability and uniqueness in its use for the clearing of frost and/or fog from windshields, the oscillator nevertheless has other uses besides clearing glass areas on vehicles for better viewing purposes.